Four of seven sub-Saharan African countries followed by researchers over the last year and a half now can track the effectiveness of HIV treatment among all patients receiving it with tests to measure the levels of virus in their bodies at least once a year, according to an update in last week’s Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report. Across those four countries — Namibia, South Africa, Kenya, and Côte d’Ivoire — and the other three — Malawi, Tanzania and Uganda — a total of 62 laboratories were enrolled to carry out the viral load testing from January 2015 to June 2016 and all countries increased the numbers of people living with HIV whose viral load was measured.

That’s significant progress, because following diagnosis of HIV, and access to treatment, the ability to determine that treatment is controlling the virus and reducing risks of illness and transmission is the last piece of the puzzle* that UNAIDS has projected must be completed in the next four years to end HIV as a global public health threat by 2030. And while western countries routinely use viral load testing to monitor HIV patients’ responses to antiretroviral medicine, low- and middle-income countries, including in southern African countries with the greatest HIV burdens have counted on the less proactive, and more affordable approach of using tests measuring patients’ immune cell — or CD4 — counts instead to see how much damage the virus is doing.

But while progress across the seven countries indicate what is possible, a breakdown of the numbers collected in each also illustrate the continuing cost, capacity and resource challenges. While the time from testing to results should be within two weeks so that issues including whether the patient is receiving treatment, and whether treatment is working can be efficiently addressed, the average test turnaround time was four to seven weeks in five of the countries — with delays caused by equipment breakdown, supply interruption, and staff shortages. While Namibia, Kenya and South Africa tested more than 85 percent of patients who were receiving antiretroviral treatment, the remaining four countries tested less than a quarter of their patients on HIV treatment.

Filling the gaps, the researchers say, will require international collaborations to supply affordable tests, supplies, and training, and planning to make the tests — and timely results — universally accessible.

*90 percent of all people with HIV to know it, 90 percent of those to be receiving treatment, and among 90 percent of those, for treatment to effectively be suppressing the virus, reducing risks of illness and transmission.